Seperate building?

[bth0mas20]

I am trying to make sense of the term "seperate building".

Im estimating a job to install a sub panel in a garage to feed outlets in the garage and future inground pool.

He wants the panel on the back wall because years from now it can feed the pool equipment on the other of the exterior wall.

The garage is back off of the house and only connected at the corners. Each building has its own exterior walls. Im making sure that I can install a 4 wire feeder in conduit (insulated egc) to this sub panel and years from now will be able to feed his pool from it. I know it says "seperate building" so I want to make sure this scenario works.

Thanks

 

[cowboyjwc]

I would say that if they share the same footings and/or slab and are connected by a roof, such as a breeze way, then they are one building.

 

[bth0mas20]

The foundation is completley seperate and the garage has its own slab floor.
their is a screened in porch connecting them and the corners of the garage and house touch.

I need to decide if its ok to install a feeder to this sub panel with an insulated conductor in pvc.

 

[LEO2854]

I am trying to make sense of the term "seperate building".

Im estimating a job to install a sub panel in a garage to feed outlets in the garage and future inground pool.

He wants the panel on the back wall because years from now it can feed the pool equipment on the other of the exterior wall.

The garage is back off of the house and only connected at the corners. Each building has its own exterior walls. Im making sure that I can install a 4 wire feeder in conduit (insulated egc) to this sub panel and years from now will be able to feed his pool from it. I know it says "seperate building" so I want to make sure this scenario works.

Thanks

Look at Exhibit 250.19 of The 2008 NEC HANDBOOK and Article 250.32 (A) (B) (C) (D)

 

[infinity]

Why do you care if they're separate or attached? Either way you'll need an EGC with the feeder. A separate structure would require a grounding electrode system.

 

[renosteinke]

I'm not sure where the issue is ...

Whether a separate building or not, you wire the panel the same - 2 hots, a neutral, and a ground. You don't bond the neutral to the ground at your new panel in either case.

The only question is: do you need a "ground rod?" (or other electrode)? If you're pouring a slab, only good things can come from putting in a UFER at the time. Maybe not required, but it won't hurt anything, and the cost is trivial. Indeed, since you said the magic word "pool," just what is an 'equipotential grid' but another form of Ufer? Bond the #$# out of it all and be done with it.

Otherwise, the 'separate structure' question can best be addressed by asking 'do I have two separate targets for lightning to strike?' If so, then you need a ground electrode - but, remember, you still need to run a ground wire with your feed, and keep the ground and neutral separate.

 

[bth0mas20]

ok I was getting confused reading seperate building in 680. I will install 4 wire insulated ground circuit in schedule 40 pvc. Also install ground rods, and keep the neutral and ground seperate in a main breaker panel.

The pool wont be installed for years so the ground rods will satisfy for now. Their is also a lightning protection system on this garage already.

 

[LarryFine]

A separate structure would require a grounding electrode system.

And a main disco or the 6-handle limit.

 

[Pierre C Belarge]

I'm not sure where the issue is ...

Whether a separate building or not, you wire the panel the same - 2 hots, a neutral, and a ground. You don't bond the neutral to the ground at your new panel in either case.

The only question is: do you need a "ground rod?" (or other electrode)? If you're pouring a slab, only good things can come from putting in a UFER at the time. Maybe not required, but it won't hurt anything, and the cost is trivial. Indeed, since you said the magic word "pool," just what is an 'equipotential grid' but another form of Ufer? Bond the #$# out of it all and be done with it.

Otherwise, the 'separate structure' question can best be addressed by asking 'do I have two separate targets for lightning to strike?' If so, then you need a ground electrode - but, remember, you still need to run a ground wire with your feed, and keep the ground and neutral separate.

How does a slab meet the requirements of 250.52(A)(3)?


Would you mind elaborating on this statement?

 

[George Stolz]

...there is a screened in porch connecting them and the corners of the garage and house touch.

If so much as a 2x4 connects the twain, they are one in my book.

I agree with Pierre, trying to make an analogy based on the psychology of a lightning bolt is confusing at best.

 

[infinity]

ok I was getting confused reading seperate building in 680. I will install 4 wire insulated ground circuit in schedule 40 pvc. Also install ground rods, and keep the neutral and ground seperate in a main breaker panel.

The pool wont be installed for years so the ground rods will satisfy for now. Their is also a lightning protection system on this garage already.

If this is an attached structure the ground rods are not required.

 

[jxofaltrds]

The foundation is completley seperate and the garage has its own slab floor.
their is a screened in porch connecting them and the corners of the garage and house touch.

I need to decide if its ok to install a feeder to this sub panel with an insulated conductor in pvc.

I would call it a seperate structure and install a ground rod, two if the conditions of 250.56 were not met.

 

[G0049]

I am trying to make sense of the term "seperate building".

Im estimating a job to install a sub panel in a garage to feed outlets in the garage and future inground pool.

He wants the panel on the back wall because years from now it can feed the pool equipment on the other of the exterior wall.

The garage is back off of the house and only connected at the corners. Each building has its own exterior walls. Im making sure that I can install a 4 wire feeder in conduit (insulated egc) to this sub panel and years from now will be able to feed his pool from it. I know it says "seperate building" so I want to make sure this scenario works.

Thanks

And that depends entirely on what the code says years from now.

 

[Pierre C Belarge]

And that depends entirely on what the code says years from now.

Exactly..seeing into the future is not easy when it comes to the code...

you would need special....glasses.

 

[renosteinke]

How does a slab qualify as a grounding electrode?

First, let's make clear that I am assuming the use of reinforcing steel or mesh in the concrete, and that it is not epoxy coated. It's probably a trivial point, but residential slabs are technically not required to have steel in them - so it's a good detail to catch.

Otherwise, a 'concrete encased electrode,' or Ufer, need not be made of copper. the use of the rebar is enough, assuming that you have enough length; simple tie wires are also enough for your connections; there's no requirement that the rebar be welded or that 'listed' connectors be used at any point apart from where the wire to the panel is tied in.

Absent the rebar, a suitable length of copper wire will make your 'ufer.'

Now, looking at pool construction: if the pool, or the deck, is a concrete pour, I see no reason that it cannot be considered the same as a foundation as for grounding. You've got the same construction, and the same minimum thicknesses. Indeed, by extending below the frost line, one might expect a pool to do even better than the usual Ufer.

Perhaps I failed to understand the objection? I believe that the "Ufer" is well established as an acceptable grounding electrode, and I'm having trouble imagining a Ufer that is not in a concrete slab. I can't imagine any situation where a ground rod is acceptable but a Ufer is not.

If I've answered the wrong question, please clarify. I am not in any position to look up a code reference.

 

[George Stolz]

I would call it a seperate structure and install a ground rod, two if the conditions of 250.56 were not met.

How are they separate structures if they are connected with a common porch?

 

[Pierre C Belarge]

How does a slab qualify as a grounding electrode?

First, let's make clear that I am assuming the use of reinforcing steel or mesh in the concrete, and that it is not epoxy coated. It's probably a trivial point, but residential slabs are technically not required to have steel in them - so it's a good detail to catch.

Otherwise, a 'concrete encased electrode,' or Ufer, need not be made of copper. the use of the rebar is enough, assuming that you have enough length; simple tie wires are also enough for your connections; there's no requirement that the rebar be welded or that 'listed' connectors be used at any point apart from where the wire to the panel is tied in.

Absent the rebar, a suitable length of copper wire will make your 'ufer.'

Now, looking at pool construction: if the pool, or the deck, is a concrete pour, I see no reason that it cannot be considered the same as a foundation as for grounding. You've got the same construction, and the same minimum thicknesses. Indeed, by extending below the frost line, one might expect a pool to do even better than the usual Ufer.

Perhaps I failed to understand the objection? I believe that the "Ufer" is well established as an acceptable grounding electrode, and I'm having trouble imagining a Ufer that is not in a concrete slab. I can't imagine any situation where a ground rod is acceptable but a Ufer is not.

If I've answered the wrong question, please clarify. I am not in any position to look up a code reference.

What you posted above is called 'subterfuge'

You have not answered the question I posed to you earlier, I will pose it again.

How does a slab meet the requirements of 250.52(A)(3)?


In the wording of 250.52(A)(3) you will find the answer.

 

[gary]

I had a similar issue a while back which was discussed here:
http://forums.mikeholt.com/showthread.php?t=95237

The local AHJ said that this house and garage, although substantially connected via a breezeway, were separate buildings because the footings were not connected. I had to provide separate Ufer grounds for the garage and house subpanels.

 

[George Stolz]

Seems as though the consensus was that your AHJ was a fruit.

Classic Post of the Week:

This makes me wonder however, if a continuous roof doesn't create one building and a continuous footing is required for it to be one building, how many buildings are there in a pole barn? :grin:

Love it!

 

[renosteinke]

No "subterfuge" intended ... as noted, I am not able to access a codebook. Perhaps you would be kind enough to post the code, and not just a citation? Perhaps then we all would get your point.